Exposure apparatus, exposure method, holographic optical element manufacturing apparatus, and holographic optical element manufacturing method

Abstract

The present invention relates to an exposure apparatus, an exposure method, a manufacturing apparatus for a holographic optical element, and a manufacturing method for a holographic optical element. The present invention produces a holographic optical element having a set diffraction efficiency. An exposure apparatus for exposing a volume hologram includes a laser light source for irradiating a volume hologram with light of a prescribed wavelength, i.e., first light, for detecting a first diffraction efficiency of the volume hologram during exposure; a power meter for detecting the amount of light of the first light; a power meter for detecting the amount of light of second light diffracted by the volume hologram; a prediction device for calculating the first diffraction efficiency based on the detection results of the power meters, and predicting a second diffraction efficiency of the volume hologram after exposure is stopped based on the calculated first diffraction efficiency; and a control device for controlling an adjusting device based on the prediction results, the adjusting device adjusting the amount of light of the laser light source, which irradiates third light for exposing the volume hologram.

Description

Technical Field

[0001] This disclosure relates to an exposure apparatus, an exposure method, an apparatus for manufacturing holographic optical elements, and a method for manufacturing holographic optical elements. Background Technology

[0002] Previously, exposure apparatuses for manufacturing holographic optical elements were known. For example, the interference exposure apparatus of Patent Document 1 includes a first laser source for exposure and a second laser source for monitoring. In Patent Document 1, light is irradiated onto a recording material from the second laser source, and the desired diffraction grating (holographic optical element) is fabricated by monitoring the intensity of the light diffracted by the recording material.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Publication No. 2006-209003 Summary of the Invention

[0004] The technical problem that the invention aims to solve However, in the fabrication of holographic optical elements, after exposure is stopped (ended), the holographic optical element is bleached to fix the diffraction grating formed by the exposure. The diffraction efficiency of the holographic optical element changes from the time exposure stops until bleaching ends. This is believed to be because the changes (chemical reactions) in the material within the holographic optical element continue even after exposure stops or during bleaching. Furthermore, the change in diffraction efficiency varies depending on the material and thickness of the holographic optical element. As a result, the diffraction efficiency of the fabricated holographic optical element will deviate.

[0005] Therefore, the purpose of this disclosure is to provide an exposure apparatus, an exposure method, and a method for manufacturing holographic optical elements that can produce holographic optical elements with a set diffraction efficiency.

[0006] Technical solutions for solving technical problems To achieve the above objectives, one embodiment of this disclosure relates to an exposure apparatus for exposing a holographic optical element. The exposure apparatus includes a first light source, a first detector, a second detector, a prediction device, a second light source, an adjustment device, and a control device. To detect the diffraction efficiency (i.e., the first diffraction efficiency) of the holographic optical element during the exposure process, the first light source irradiates the holographic optical element with light of a predetermined wavelength (i.e., first light). The first detector detects the amount of the first light, and the second detector detects the amount of the first light diffracted by the holographic optical element (i.e., the second light). The prediction device calculates the first diffraction efficiency based on the detection results of the first and second detectors. Based on the calculated first diffraction efficiency, it predicts the diffraction efficiency (i.e., the second diffraction efficiency) of the holographic optical element after exposure has stopped. The second light source irradiates the holographic optical element with third light for exposing the holographic optical element. The adjustment device adjusts the amount of the third light. The control device controls the adjustment device based on the prediction result of the prediction device.

[0007] The effects of the invention According to this disclosure, it is possible to fabricate holographic optical elements with a predetermined diffraction efficiency. Attached Figure Description

[0008] Figure 1 This is a side view of the exposure apparatus according to the first embodiment.

[0009] Figure 2 This is a flowchart illustrating the operation of the exposure apparatus according to the first embodiment.

[0010] Figure 3 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the first embodiment.

[0011] Figure 4 This is a side view of the exposure apparatus according to the second embodiment.

[0012] Figure 5 This is a flowchart illustrating the operation of the exposure apparatus according to the second embodiment.

[0013] Figure 6 This is a graph illustrating an example of the variation in the predicted value of the diffraction efficiency of the volume hologram according to the second embodiment.

[0014] Figure 7 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the second embodiment.

[0015] Figure 8This is a graph showing an example of the change in the amount of light emitted by a laser irradiating a volumetric hologram according to the second embodiment.

[0016] Figure 9 This is a side view of the exposure apparatus according to the third embodiment.

[0017] Figure 10 This is a graph illustrating an example of the variation in the predicted value of the diffraction efficiency of the volume hologram according to the third embodiment.

[0018] Figure 11 This is a flowchart illustrating the operation of the exposure apparatus according to the third embodiment.

[0019] Figure 12 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the third embodiment.

[0020] Figure 13 This is a graph showing an example of the change in the amount of bleaching light irradiating the volume hologram according to the third embodiment.

[0021] Figure 14 This is a side view of the exposure apparatus according to the fourth embodiment.

[0022] Figure 15 This is a flowchart illustrating the operation of the exposure apparatus according to the fourth embodiment.

[0023] Figure 16 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the fourth embodiment.

[0024] Figure 17 This is a graph showing an example of the change in the amount of light emitted by a laser irradiating a volumetric hologram according to the fourth embodiment.

[0025] Figure 18 This is a graph showing an example of the change in the amount of bleaching light irradiating the volume hologram according to the fourth embodiment.

[0026] Symbol Explanation 1 – Laser source (second light source); 2 – Branch mirror; 3, 4 – Reflector; 5 – Volume hologram (holographic optical element); 6 – Laser source (first light source); 7 – Beam splitter (optical element); 8 – Power meter (first detector); 9 – Power meter (second detector); 10 – Control device (prediction device, control device); 11 – Shutter; 12 – Power meter; 13 – Bleaching light source (third light source); 15 – Attenuator (adjustment device); 15a – λ / 2 wavestop; 15b – Polarizing beam splitter; L1 (L1a) – Laser (third beam); L6 – Laser (first beam); L7 – Laser (second beam); L8 – Bleaching light. Detailed Implementation

[0027] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The following description of preferred embodiments is merely illustrative and is not intended to limit the invention, its application, or its uses. It should be noted that in the following description, the same reference numerals will be used for the same parts, and detailed descriptions will be appropriately omitted.

[0028] It should be noted that, unlike two-dimensional diffraction gratings with fine periodic bumps and depressions arranged on a surface, the volume holograms used in this disclosure (volume holograms) Figure 5 The refractive index distribution in the volume hologram is recorded in a three-dimensional, sinusoidal pattern. By controlling the direction and period of this sinusoidal wave, as well as the amplitude of the refractive index difference, the light distribution of the volume hologram can be controlled. It should be noted that, for ease of explanation, the refractive index distribution recorded in the volume hologram is sinusoidal in this disclosure, but the refractive index distribution recorded in the volume hologram is not limited to a sinusoidal pattern; it can also be other shapes or complex shapes.

[0029] Furthermore, the exposure method and the manufacturing method of holographic optical elements are realized using the exposure apparatus described below.

[0030] (First Implementation) (Overall structure of the exposure device) Figure 1 This is a side view of the exposure apparatus according to the first embodiment. It should be noted that... Figure 1 In this diagram, the direction of laser L3 is set as the X direction, the direction of laser L2 (object light) is set as the Y direction, and the direction perpendicular to both the X and Y directions (the depth direction of the paper plane) is set as the Z direction. Additionally, in... Figure 1 In the diagram, dashed arrows represent light emanating from laser sources 1 and 6.

[0031] like Figure 1 As shown, the exposure apparatus according to the first embodiment includes a laser light source 1 (laser light source for exposure), a branch mirror 2, mirrors 3 and 4, and a volume hologram. Figure 5The system includes a holographic optical element, a laser light source 6 (for monitoring), a beam splitter 7 (optical element), a power meter 8 (first detector), a power meter 9 (second detector), a control device 10 (prediction device), and a shutter 11. It should be noted that volume holography... Figure 5 It is a volumetric hologram that is exposed (manufactured) by this exposure device.

[0032] Laser source 1 is the light source that illuminates laser L1 (parallel light, third light) through the split mirror 2. Laser source 1 is a highly coherent laser source. Therefore, after laser L1 is split into lasers L2 and L3 by the split mirror 2 (described later), even if lasers L2 and L3 deviate from the same optical path, the light may still interfere with each other. In addition, laser L1 has the characteristics of linearly polarized light, and if the polarization ratio is insufficient, wavestops or polarizing plates can be inserted to control the polarization direction.

[0033] A shutter 11 for blocking the laser L1 is provided between the laser source 1 and the branch mirror 2. The laser source 1 and the shutter 11 operate by receiving signals from the control device 10. It should be noted that the shutter 11 can also be integrated with the laser source 1.

[0034] It should be noted that an optical system for making the laser L1 parallel can also be provided between the laser source 1 and the branch mirror 2. For example, a condenser lens and a collimating lens can also be provided between the laser source 1 and the branch mirror 2. In this case, the condenser lens focuses the laser L1 from the laser source 1 into diffused light. Then, the collimating lens makes the laser L1 diffused by the condenser lens parallel light.

[0035] The splitter mirror 2 branches the laser L1 emitted from the laser source 1 into two beams. Specifically, the splitter mirror 2 splits the laser L1 into laser L2 (object light) and laser L3 (reference light). For example, the splitter mirror 2 is composed of a polarizing beam splitter, etc., which reflects the linearly polarized light (laser L2, such as S-polarized light) in the first polarization direction of laser L1, and allows the linearly polarized light (laser L3, such as P-polarized light) in the second polarization direction to pass through.

[0036] Reflector 3 is a reflector that reflects the laser L2 reflected by branch mirror 2. For example... Figure 1 As shown, the reflector 3 is formed in a planar shape. Laser L2 is reflected by the reflector 3 and illuminates the volume hologram. Figure 5 It should be noted that mirror 3 can also be a curved surface.

[0037] Reflector 4 is a reflector that reflects the laser L3 after it passes through branch mirror 2. For example... Figure 1 As shown, the reflector 4 is planar. Laser L3 is reflected by the reflector 4 and illuminates the volume hologram. Figure 5It should be noted that mirror 4 can also be a curved surface.

[0038] Volume holography Figure 5 This is a volumetric hologram created by exposing (manufacturing) using this exposure device. Volumetric holography. Figure 5 It includes a photopolymer 5a and a substrate 5b. The photopolymer 5a is formed, for example, from an optical material whose refractive index changes when it receives visible light. The substrate 5b is a flat plate with high transmittance, such as quartz or optical glass.

[0039] In this embodiment, when performing volume holography... Figure 5 During exposure, through volumetric holography Figure 5 Irradiating lasers L2 (object light) and L3 (reference light) creates interference fringes (refractive index distribution) on the photopolymer 5a. In other words, through volume holography... Figure 5 Irradiation with lasers L2 and L3, volume holography Figure 5 It was exposed. Afterwards, through volumetric holography... Figure 5 By irradiating the material with ultraviolet light, the interference fringes remain unchanged. This allows for the fabrication of volume holograms. Figure 5 .

[0040] It should be noted that, as Figure 1 As shown, lasers L2 and L3 illuminate the volume hologram. Figure 5 At this time, the light can be parallel, divergent, or convergent. For example, by making reflectors 3 and 4 curved surfaces, or by arranging lenses or other optical elements in front of and behind reflectors 3 and 4, reflectors 3 and 4 can be made to produce divergent or convergent light. Furthermore, in Figure 1 In the process, lasers L2 and L3 illuminate the volume hologram at an angle of 90° to each other. Figure 5 However, it is not limited to this; the angle between the mutual illumination directions can be any angle. Furthermore, it can also be a laser L2 from a volumetric hologram. Figure 5 Irradiation from the surface side (or back side) of the volumetric hologram; laser L3 from the volumetric hologram. Figure 5 Irradiate the back side (or surface side).

[0041] Laser source 6 is the light source that illuminates laser L4 onto beam splitter 7. Laser L4 is used for volumetric holography during the exposure process. Figure 5 Irradiation will not affect the volume hologram Figure 5 The diffraction efficiency affects the wavelength range of light (e.g., infrared light around 800nm–1500nm). Laser source 6 is used to detect volumetric holography during the exposure process. Figure 5 A light source with high diffraction efficiency. At this point, laser L4 is incident on the volume hologram from an angle satisfying the Bragg angle condition. Figure 5This is to allow diffraction to occur. It should be noted that the laser L4 emitted by the laser source 6 can also be light outside the aforementioned wavelength range.

[0042] Beam splitter 7 branches (splits) the laser L4 emitted from laser source 6 into two beams. Specifically, beam splitter 7 branches laser L4 into lasers L5 and L6. It should be noted that a semi-reflective mirror can also be used instead of beam splitter 7. Other optical elements can also be used as long as they enable the laser L4 emitted from laser source 6 to be split into two beams.

[0043] Power meters 8 and 9 are, for example, power meters that measure the amount of light received. It should be noted that power meters 8 and 9 can be any detector as long as they can detect the amount of light from lasers L5 and L7, respectively.

[0044] The power meter 8 receives the laser L5 branched out by the beam splitter 7 and outputs data representing the amount of light received by the laser L5 to the control device 10.

[0045] The incident volume hologram of laser L6 (first beam) branched from beam splitter 7 Figure 5 Then, laser L6 is subjected to volume holography. Figure 5 After diffraction, the light is incident on power meter 9 as laser L7 (second light). Power meter 9 outputs data indicating the amount of light received by laser L7 to control device 10.

[0046] The control device 10 is, for example, a computer including a CPU, ROM, RAM, etc. The control device 10 controls the volume hologram based on data output from the power meters 8 and 9. Figure 5 The exposure process. Specifically, the control device 10, based on the volume hologram... Figure 5 The predicted value of the diffraction efficiency (details to be described later) is used to control the laser source 1 and the shutter 11.

[0047] (Regarding the operation of the exposure device) Figure 2 This is a flowchart illustrating the operation of the exposure apparatus according to this embodiment.

[0048] First, the control device 10 receives the volumetric hologram to be produced from the user via an operation unit (not shown). Figure 5 The set value for the diffraction efficiency is input (step S1). At this time, the volume hologram received by the control device 10... Figure 5 The diffraction efficiency is set at a value for volumetric holography in the green band (e.g., around 500nm–550nm). Figure 5 The diffraction efficiency is set to a certain value. Then, the control device 10 inputs the volume holographic data. Figure 5The set value of the diffraction efficiency is converted into volume holography in the infrared band (e.g., light in the infrared band around 800nm ​​to 1500nm). Figure 5 The set value for diffraction efficiency. The control device 10 uses the converted volumetric hologram in the infrared band in the following processing. Figure 5 The set value of the diffraction efficiency.

[0049] Control device 10 controls each part of this exposure apparatus to begin the exposure of the volume hologram. Figure 5 Exposure (step S2). Specifically, the control device 10 begins exposure of the volumetric hologram. Figure 5 During exposure, the laser light source 1 and shutter 11 are controlled so that laser L1 is irradiated from the laser light source 1 and the shutter 11 is in the open state.

[0050] Based on the data output from the power meters 8 and 9, the control device 10 calculates the volume hologram. Figure 5 The diffraction efficiency (step S3). Specifically, the control device 10 calculates the volumetric holography during the exposure process based on the data output from the power meters 8 and 9, respectively. Figure 5 The diffraction efficiency (first diffraction efficiency). Volume holography. Figure 5 The diffraction efficiency is calculated by dividing the amount of light from laser L7 (the second light) by the amount of light from laser L6 (the first light). In other words, when laser L4 is emitted from the monitoring laser source 6, the volume hologram... Figure 5 The diffraction efficiency is calculated by dividing the amount of light from laser L7 by the amount of light from laser L6, where laser L7 is the light obtained through volume holography. Figure 5 The diffracted light, laser L6 is a volume hologram Figure 5 The incident light. In this embodiment, the amount of light from laser L7 is included in the data output from power meter 9. Furthermore, since the amount of light from laser L6 is correlated with the amount of light from laser L5, the amount of light from laser L6 can be measured based on the data output from power meter 8 (the amount of light from laser L5).

[0051] However, in Patent Document 1, since the diffraction efficiency of the holographic optical element is measured (monitored) solely by the intensity of the light diffracted by the recording material from the light emitted from the second laser source, the diffraction efficiency of the holographic optical element cannot be accurately measured if the amount of light emitted from the second laser source changes. As a result, the diffraction efficiency of the holographic optical element deviates.

[0052] For example, when the output of the second laser source varies by about ±1%, the diffraction efficiency of the holographic optical element will deviate by about ±1%. In this case, it cannot be used in applications requiring high-quality standards for the holographic optical element. For instance, if used in vehicles, the deviation in diffraction efficiency needs to be suppressed to about ±3%. If the diffraction efficiency of the holographic diffracting element deviates by about ±1%, it will significantly affect its quality. Therefore, it is necessary to accurately measure the diffraction efficiency of the holographic optical element during the exposure process.

[0053] Therefore, in this embodiment, volume holography Figure 5 The diffraction efficiency is based on volume holography. Figure 5 The diffracted light, i.e., the measured value of the light intensity of laser L6 and the volume hologram, is diffracted. Figure 5 The diffraction efficiency of the holographic optical element during the exposure process is calculated based on the measured value of the incident light, i.e., the light intensity of laser L6.

[0054] Control device 10 predicts volumetric holography Figure 5 The predicted value of the diffraction efficiency (second diffraction efficiency) is obtained (step S4). Specifically, based on the diffraction efficiency calculated in step S3, the control device 10 calculates the measured value and the change in the diffraction efficiency. Then, the control device 10 sets the measured value of the diffraction efficiency + the change × coefficient as the volume hologram. Figure 5 The predicted values. It should be noted that the coefficients at this point are determined through various implementation results or machine learning (AI), etc.

[0055] Control device 10 determines volume holography Figure 5 Is the predicted diffraction efficiency of volume holography... Figure 5 The diffraction efficiency is above the set value (step S5). The control device 10 operates in volume holography... Figure 5 The predicted diffraction efficiency is lower than that of volume holography. Figure 5 If the diffraction efficiency is within the set value (No in step S5), return to step S3. The control device 10 operates in volume holography... Figure 5 The predicted diffraction efficiency is for volume holography. Figure 5 If the diffraction efficiency is above the set value (Yes in step S5), stop (end) the volume holography. Figure 5 Exposure (step S6). Specifically, the control device 10 stops the exposure of the volumetric hologram. Figure 5 During exposure, the laser source 1 and shutter 11 are controlled so that the laser source 1 stops irradiating laser L1 (the third light), and the shutter 11 is closed. In other words, the control device 10 controls the volume hologram based on the calculated diffraction efficiency. Figure 5 The exposure process (here, the exposure stops (ends)).

[0056] Subsequently, through volume holography Figure 5 By irradiating the sample with ultraviolet light, the interference fringes formed are kept unchanged.

[0057] Figure 3 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the first embodiment. Figure 3 The diagram illustrates the diffraction efficiencies of volume holograms 51-53, which vary in material and thickness. Figure 3 In the process, exposure of volume holograms 51 to 53 is stopped at times t1 to t3 respectively.

[0058] However, even after the exposure light is stopped to halt (end) the exposure, the change in diffraction efficiency of the holographic optical element continues for a specified period. This is believed to be because the changes (chemical reactions) in the materials within the holographic optical element continue even after exposure has ceased. Furthermore, the change in diffraction efficiency varies depending on the materials and thickness of the holographic optical element. As a result, the diffraction efficiency of the fabricated holographic optical element will deviate.

[0059] Specifically, such as Figure 3 As shown, the diffraction efficiency of volume holograms 51-53 begins to increase when exposure begins. Then, after exposure is stopped (ended), the diffraction efficiency in volume holograms 51-53 continues to increase. This is believed to be because the material changes (chemical reactions) within the volume holograms continue even after exposure stops. In other words, it can be said that the diffraction efficiency does not immediately stop (stabilize) even after exposure to the volume holograms is stopped. In particular, the change in diffraction efficiency of volume holograms varies depending on their material and thickness.

[0060] Therefore, in this embodiment, the control device 10 calculates the volume hologram based on the measurement results of power meters 8 and 9 (the measured values ​​of the light intensity of lasers L6 and L7). Figure 5 The diffraction efficiency is used to predict the volumetric hologram after exposure stops. Figure 5 The diffraction efficiency was determined, and the calculation of volume holography was stopped based on this prediction. Figure 5 The exposure. That is to say, the control device 10 is based on the volume hologram. Figure 5 The calculation results of the diffraction efficiency are used to control the exposure process of the holographic optical element. Therefore, even volumetric holograms with different materials and thicknesses can be produced with the set diffraction efficiency.

[0061] (First Implementation) (Overall structure of the exposure device) Figure 4 This is a side view of the exposure apparatus according to the second embodiment. Figure 1In comparison, Figure 4 In this configuration, an attenuator 15 is installed between the laser source 1 and the branch mirror 2 to replace the shutter 11.

[0062] Specifically, attenuator 15 is an adjustment device that controls the amount of laser light L1 output from laser source 1. Attenuator 15 includes a λ / 2 wavestop 15a and a polarization beam splitter 15b.

[0063] A λ / 2 wavestop 15a is a wavestop that changes the polarization direction of incident light. A polarization beam splitter 15b branches the incident light into S-polarized light and P-polarized light. If laser L1 is incident on the λ / 2 wavestop 15a, its polarization direction changes. Then, laser L1 is split into S-polarized light (laser L1a) and P-polarized light (laser L1b) by the polarization beam splitter 15b. Laser L1a then enters the splitting mirror 2, and laser L1b enters the power meter 12. The power meter 12 measures the amount of light received, specifically the amount of light from laser L1b.

[0064] Here, the λ / 2 wavestop 15a can rotate about the X-axis. By rotating the λ / 2 wavestop 15a, the polarization direction of laser L1 can be changed, thus changing the light intensity of lasers L1a and L1b. At this time, the light intensity of laser L1a can be calculated from the light intensity of laser L1b. It should be noted that the control device 10 can measure the light intensity of laser L1 (L1a) based on the measurement results of the power meter 12.

[0065] It should be noted that an ND filter can also be used instead of attenuator 15. In this case, the amount of light from laser L1 can also be controlled.

[0066] Alternatively, the attenuator 15 can be omitted, and the laser source 1 can include a light quantity control device to control the light quantity (output) of the laser L1. The light quantity control device can also be controlled by the control device 10 to change the light quantity of the laser L1.

[0067] Based on the data output from the power meters 8 and 9, the control device 10 controls the volume hologram. Figure 5 The exposure process. Specifically, the control device 10, based on the volume hologram... Figure 5 The predicted value of the diffraction efficiency is used to control attenuator 15 (λ / 2 wavestop 15a).

[0068] (Regarding the operation of the exposure device) Figure 5 This is a flowchart illustrating the operation of the exposure apparatus according to the second embodiment.

[0069] First, the control device 10 receives the volumetric hologram to be produced from the user via an operation unit (not shown). Figure 5The set value for the diffraction efficiency is input (step S11). At this time, the volume hologram received by the control device 10... Figure 5 The diffraction efficiency is set at a value for volumetric holography in the green band (e.g., around 500nm–550nm). Figure 5 The diffraction efficiency is set to a certain value. Then, the control device 10 inputs the volume holographic data. Figure 5 The set value of the diffraction efficiency is converted into volume holography in the infrared band (e.g., light in the infrared band around 800nm ​​to 1500nm). Figure 5 The set value for diffraction efficiency. The control device 10 uses the converted volumetric hologram in the infrared band in the following processing. Figure 5 The set value of the diffraction efficiency.

[0070] In addition, in step S11, the control device 10 sets the first threshold and the second threshold, which will be described later, based on the input of the set value of the diffraction efficiency.

[0071] Control device 10 controls each part of this exposure apparatus to begin the exposure of the volume hologram. Figure 5 Exposure (step S12). Specifically, the control device 10 controls the attenuator 15 (specifically, rotates the λ / 2 wave blocking plate 15a) so that the amount of light emitted from the laser source 1, the laser L1 (L1a) reaches a specified value.

[0072] Based on the data output from the power meters 8 and 9, the control device 10 calculates the volume hologram. Figure 5 The diffraction efficiency (first diffraction efficiency) is calculated (step S13). Specifically, the control device 10 calculates the volumetric holography during the exposure process based on the data output from the power meters 8 and 9, respectively. Figure 5 The diffraction efficiency. Volume holography. Figure 5 The diffraction efficiency is calculated by dividing the amount of light from laser L7 (the second light) by the amount of light from laser L6 (the first light). In other words, when laser L4 is emitted from the monitoring laser source 6, the volume hologram... Figure 5 The diffraction efficiency is calculated by dividing the amount of light from laser L7 by the amount of light from laser L6, where laser L7 is the light obtained through volume holography. Figure 5 The diffracted light, laser L6 is a volume hologram Figure 5 The incident light. In this embodiment, the amount of light from laser L7 is included in the data output from power meter 9. Furthermore, since the amount of light from laser L6 is correlated with the amount of light from laser L5, the amount of light from laser L6 can be measured based on the data output from power meter 8 (the amount of light from laser L5). That is, in this embodiment, due to volume holography... Figure 5 The diffraction efficiency is based on volume holography. Figure 5The diffracted light, i.e., the measured value of the light intensity of laser L6 and the volume hologram, is diffracted. Figure 5 The diffraction efficiency of the holographic optical element during the exposure process is calculated based on the measured value of the incident light, i.e., the light intensity of laser L6.

[0073] Control device 10 predicts volumetric holography Figure 5 The predicted value of the diffraction efficiency (second diffraction efficiency) is obtained (step S14). Specifically, the control device 10 calculates the measured value and the change in diffraction efficiency based on the diffraction efficiency calculated in step S13. Then, the control device 10 sets the measured value of the diffraction efficiency + the change × coefficient as the volume hologram. Figure 5 The predicted values. It should be noted that the coefficients at this point are determined through various implementation results or machine learning (AI), etc.

[0074] Control device 10 controls attenuator 15 to enable volume holography. Figure 5 The predicted diffraction efficiency does not exceed that of volume holography. Figure 5 The set value of the diffraction efficiency.

[0075] Specifically, the control device 10 determines the volume hologram. Figure 5 Whether the predicted value of the diffraction efficiency is above the first threshold (step S15). In volume holography Figure 5 If the predicted diffraction efficiency is less than the first threshold (No in step S15), the control device 10 controls the attenuator 15 to increase or maintain the intensity of laser L1 according to the first difference (step S16). Specifically, the control device 10 rotates the λ / v waveguide 15a to increase or maintain the intensity of laser L1. After step S16, the process returns to step S13.

[0076] Volume holography Figure 5 If the predicted diffraction efficiency is above a first threshold ("Yes" in step S15), the control device 10 controls the attenuator 15 to reduce the amount of laser L1 according to the first difference (step S17). Specifically, the control device 10 calculates the first difference. The first difference is the ratio (percentage (%)) of the second reference value to the first reference value. The first reference value is the value obtained by subtracting the first threshold from the set value of the diffraction efficiency, and the second reference value is the value obtained by subtracting the predicted value of the diffraction efficiency from the set value of the diffraction efficiency (refer to...). Figure 6 The control device 10 rotates the λ / 2 wavestop plate 15a to reduce the calculated amount of laser light L1.

[0077] Control device 10 determines volume holography Figure 5Whether the predicted value of the diffraction efficiency is above the second threshold (step S18). The control device 10 determines whether the volume hologram is... Figure 5 If the predicted diffraction efficiency is less than the second threshold (No in step S18), return to step S13. The control device 10 determines that the volume hologram... Figure 5 If the predicted diffraction efficiency is above the second threshold ("Yes" in step S18), the process ends. Specifically, the control device 10 controls the laser source 1 to stop irradiating the laser L1 (that is, to end the process of volume holography). Figure 5 (Exposure). For example, the second threshold is set to be approximately 0.1% of the first difference.

[0078] In other words, the first threshold is the threshold described below, which is used to determine whether to irradiate the volumetric hologram. Figure 5 Does the amount of light from laser L1 remain constant or increase, or does it irradiate the volumetric hologram? Figure 5 The benchmark for reducing the amount of light emitted by laser L1. Additionally, the second threshold is a threshold as described below, which serves as the basis for reducing the amount of light emitted by the volumetric hologram. Figure 5 The laser L1 stops, that is, the laser stops affecting the volume hologram. Figure 5 The benchmark for exposure.

[0079] Subsequently, through volume holography Figure 5 The material is bleached and treated (fixed, stabilized) to ensure that the resulting diffraction grating (interference fringes) remains unchanged.

[0080] Figure 6 (a) ~ Figure 6 (c) is a graph illustrating an example of the variation in the predicted value of the diffraction efficiency of the volume hologram according to the second embodiment. Figure 6 (a) ~ Figure 6 In (c), times t11 to t13 are the times calculated in step S13 for the volume hologram. Figure 5 The diffraction efficiency at the current moment. Figure 6 (a) ~ Figure 6 In (c), time t14 is the time when the volume hologram is calculated in step S14. Figure 5 The baseline time for the predicted diffraction efficiency (e.g., volume holography). Figure 5 (the moment when the diffraction efficiency is stable). That is, in the second embodiment, the volume holography calculated at times t11 to t13 is used. Figure 5 Based on the diffraction efficiency (step S13), the volume hologram at time t14 is predicted. Figure 5 The diffraction efficiency (step S14). It should be noted that, in Figure 6 (a) ~ Figure 6In (c), time t0 is the start of the volume holography. Figure 5 The moment of its exposure.

[0081] Specifically, such as Figure 6 As shown in (a), due to the volume holography at time t14 Figure 5 The predicted diffraction efficiency is less than the first threshold (No in step S15), therefore the control device 10 maintains (or increases) the amount of light from laser L1 (step S16). Thus, the volume holography after time t11... Figure 5 The rate of change of diffraction efficiency increases. Afterwards, as... Figure 6 As shown in (b), due to the volume holography at time t14 Figure 5 The predicted diffraction efficiency is above the first threshold ("Yes" in step S15) and below the second threshold ("No" in step S18). Therefore, the control device 10 reduces the amount of laser L1 based on the first difference (step S17). Thus, the volume hologram after time t12... Figure 5 The rate of change of diffraction efficiency decreases. Then, as... Figure 6 As shown in (c), due to the volume holography at time t14 Figure 5 The predicted value of the diffraction efficiency is above the second threshold ("Yes" in step S18), therefore the control device 10 controls the laser source 1 to stop irradiating the laser L1.

[0082] Figure 7 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the second embodiment. Figure 8 This is a graph showing an example of the change in the amount of light emitted by a laser irradiating a volumetric hologram according to the second embodiment. Figure 7 The diagram illustrates the diffraction efficiency of volume holograms 54-56, which have different materials and thicknesses. Figure 8 The diagram illustrates the amount of light emitted by laser L1 when illuminating volume holograms 54-56 (that is, the sum of the amounts of light emitted by laser L2 and laser L3).

[0083] like Figure 7 and Figure 8 As shown, at time t0, exposure of volume holograms 54-56 begins. Upon initial exposure, the intensity of laser L1 increases to a predetermined value. After a period of time from time t0, the diffraction efficiency of volume holograms 54-56 begins to increase. Then, by time t1, the intensity of laser L1 decreases. Afterward, bleaching of volume holograms 54-56 begins from time t1. Thus, volume holograms with the predetermined diffraction efficiency are manufactured.

[0084] However, in the fabrication of holographic optical elements, after exposure to the holographic optical element stops (ends), it is bleached to fix the diffraction grating formed by the exposure. During the period from the end of exposure to the start of bleaching, the diffraction efficiency of the holographic optical element changes. This is believed to be because the changes (chemical reactions) in the material within the holographic optical element continue even after exposure stops. Furthermore, the change in diffraction efficiency varies depending on the material and thickness of the holographic optical element. As a result, the diffraction efficiency of the fabricated holographic optical element will deviate.

[0085] Therefore, in this embodiment, the control device 10 calculates the volume hologram based on the measurement results of power meters 8 and 9 (the measured values ​​of the light intensity of lasers L6 and L7). Figure 5 The diffraction efficiency, based on the volumetric holography after exposure stops. Figure 5 The predicted value of the diffraction efficiency is used to control the amount of light emitted by attenuator 15 (laser L1). Therefore, even volume holograms with different materials and thicknesses can be produced with the set diffraction efficiency.

[0086] Furthermore, the amount of light emitted by the laser L1, which is used to expose the volume hologram, is gradually reduced at the beginning of bleaching. This shortens the period from when the exposure of the volume hologram stops until the start of bleaching, thus suppressing changes in the diffraction efficiency of the volume hologram during this period.

[0087] (Third implementation method) Figure 9 This is a side view of the exposure apparatus according to the third embodiment. Figure 1 In comparison, Figure 9 The shutter 11 is omitted, and a bleaching light source 13 (third light source) is provided.

[0088] 13 pairs of volumetric holograms for bleaching light source Figure 5 Bleached light L8 is used to fix (fix) the diffraction grating (interference fringes). For example, the bleaching light source 13 includes at least one of a UV light source composed of an LED or the like and a white light source.

[0089] In the third embodiment, the control device 10 is based on volume holography. Figure 5 The predicted value of the diffraction efficiency is used to control the bleaching light source 13.

[0090] (Regarding the operation of the exposure device) Figure 10 This is a flowchart illustrating the operation of the exposure apparatus according to the third embodiment. Figure 5 In comparison, Figure 10In step S11, step S21 is executed after step S12, replacing steps S15 to S18 and executing steps S51, S61, S71, and S81. It should be noted that in step S11, the control device 10 sets the third threshold and the fourth threshold, which will be described later, based on the input of the diffraction efficiency set value.

[0091] In step S21, the control device 10 begins to process the volume hologram. Figure 5 Bleaching. Specifically, the control device 10 controls the bleaching light source 13 to perform volume holography. Figure 5 Irradiate with bleaching light L8.

[0092] After step S51, the control device 10 controls the bleaching light source 13 to make the volume holographic... Figure 5 The predicted value of the diffraction efficiency (second diffraction efficiency) does not exceed that of the volume hologram. Figure 5 The set value of the diffraction efficiency (first diffraction efficiency).

[0093] Specifically, the control device 10 determines the volume hologram. Figure 5 Whether the predicted value of the diffraction efficiency is above the third threshold (step S51). In volume holography Figure 5 If the predicted diffraction efficiency is less than the third threshold (No in step S51), the control device 10 controls the bleaching light source 13 to reduce or maintain the amount of bleaching light L8 (step S61). After step S61, return to step S13.

[0094] Volume holography Figure 5 If the predicted diffraction efficiency is above the third threshold ("Yes" in step S61), the control device 10 controls the bleaching light source 13 to increase the amount of bleaching light L8 (step S71). Specifically, the control device 10 calculates a first difference. The first difference is the ratio (percentage (%)) of the second reference value to the first reference value. The first reference value is the value obtained by subtracting the third threshold from the set value of the diffraction efficiency, and the second reference value is the value obtained by subtracting the predicted value of the diffraction efficiency from the set value of the diffraction efficiency (refer to...). Figure 11 ).

[0095] Control device 10 determines volume holography Figure 5 Whether the predicted value of the diffraction efficiency is above the fourth threshold (step S81). The control device 10 determines whether the volume hologram is... Figure 5 If the predicted diffraction efficiency is less than the fourth threshold (No in step S81), return to step S13. The control device 10 determines that the volume hologram... Figure 5 If the predicted diffraction efficiency is above the fourth threshold (Yes in step S81), the processing ends. Afterwards, the processing of the volume hologram ends. Figure 5Exposure and bleaching. For example, the fourth threshold is set to be approximately 0.1% of the first difference.

[0096] In other words, the third threshold is the threshold described below, which is used to determine whether to irradiate the volumetric hologram. Figure 5 Does the amount of bleaching light L8 remain the same or decrease, or does it illuminate the volume hologram? Figure 5 The baseline for increasing the amount of bleaching light L8. The fourth threshold is the threshold described below, which becomes the threshold used to stop the main processing (to irradiate the volume hologram). Figure 5 The baseline for the treatment is the bleaching light L8 light intensity increase treatment.

[0097] It should be noted that in steps S61 and S71, when the bleaching light source 13 is composed of a UV light source and a white light source, the control device 10 can also adjust the volume based on the holographic effect. Figure 5 The predicted diffraction efficiency is used to control the light intensity of the UV light source and the white light source, respectively.

[0098] Figure 11 (a) ~ Figure 11 (c) is a graph illustrating an example of the variation in the predicted value of the diffraction efficiency of the volume hologram according to the third embodiment. Figure 11 (a) ~ Figure 11 In (c), times t15 to t17 are the times when the volume hologram is calculated in step S3. Figure 5 The diffraction efficiency at the current moment. Figure 11 (a) ~ Figure 11 In (c), time t18 is the time when the volume hologram is calculated in step S14. Figure 5 The baseline time for the predicted diffraction efficiency (e.g., volume holography). Figure 5 (the moment when the diffraction efficiency is stable). That is, in the second embodiment, the volume holography calculated at times t15 to t17 is used. Figure 5 Based on the diffraction efficiency (step S13), the volume hologram at time t18 is predicted. Figure 5 The diffraction efficiency (step S14). It should be noted that, in Figure 11 (a) ~ Figure 11 In (c), time t0 is the start of the volume holography. Figure 5 The moment of exposure.

[0099] Specifically, such as Figure 11 As shown in (a), due to the volume holography at time t18 Figure 5 The predicted diffraction efficiency is less than the third threshold (No in step S15), therefore the control device 10 maintains (or reduces) the amount of bleached light L8 (step S61). Thus, the volumetric holography after time t15... Figure 5The rate of change of diffraction efficiency increases. Afterwards, as... Figure 11 As shown in (b), due to the volume holography at time t18 Figure 5 The predicted diffraction efficiency is above the third threshold ("Yes" in step S51) and below the fourth threshold ("No" in step S81). Therefore, the control device 10 reduces the amount of bleaching light L8 according to the first difference (step S71). Thus, the volume hologram after time t16... Figure 5 The rate of change of diffraction efficiency decreases. Then, as... Figure 11 As shown in (c), due to the volume holography at time t18 Figure 5 The predicted diffraction efficiency is above the fourth threshold ("Yes" in step S81), therefore the main processing ends.

[0100] Figure 12 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the third embodiment. Figure 13 This is a graph showing an example of the change in the amount of bleaching light irradiating the volume hologram according to the third embodiment. Figure 12 The diffraction efficiency of volume holograms 57–59, which have different materials and thicknesses, is illustrated. Figure 13 The amount of bleached light L8 irradiated onto volume holograms 57–59 is shown.

[0101] like Figure 12 and Figure 13 As shown, exposure of volume holograms 57-59 begins at time t0. After a period of time from time t0, the diffraction efficiency of volume holograms 57-59 begins to increase. Then, bleaching of volume holograms 57-59 begins at times t2-t4. Finally, bleaching of volume holograms 57-59 ends at time t5. Thus, volume holograms with the set diffraction efficiency are produced.

[0102] However, in the fabrication of holographic optical elements, after exposure to the holographic optical element is stopped (ended), it is bleached to fix the diffraction grating formed by the exposure. During the bleaching process, the diffraction efficiency of the holographic optical element also changes. This is believed to be because the changes (chemical reactions) in the materials within the holographic optical element continue even during bleaching. Furthermore, the change in diffraction efficiency varies depending on the materials and thickness of the holographic optical element. As a result, the diffraction efficiency of the fabricated holographic optical element will deviate.

[0103] Therefore, in this embodiment, the control device 10 calculates the volume hologram based on the measurement results of power meters 8 and 9 (the measured values ​​of the light intensity of lasers L6 and L7). Figure 5The diffraction efficiency, and based on the volumetric holography after exposure stops. Figure 5 The predicted value of the diffraction efficiency is used to control the amount of light from the bleaching light source 13 (bleaching light L8). Therefore, even volume holograms with different materials and thicknesses can be produced with the set diffraction efficiency.

[0104] Furthermore, the volume hologram is bleached during the exposure process. This suppresses the influence of changes in the diffraction efficiency of the volume hologram during the bleaching process.

[0105] (Fourth Implementation) Figure 14 This is a side view of the exposure apparatus according to the fourth embodiment. Figure 4 In comparison, Figure 14 A bleaching light source 13 is also provided. It should be noted that the bleaching light source 13 has the same structure as the bleaching light source in the third embodiment.

[0106] In the fourth embodiment, the control device 10 is based on volume holography. Figure 5 The predicted value of the diffraction efficiency is used to control the attenuator 15 and the bleaching light source 13.

[0107] (Regarding the operation of the exposure device) Figure 15 This is a flowchart illustrating the operation of the exposure apparatus according to the fourth embodiment. Figure 5 In comparison, Figure 15 In this process, step S21 is executed after step S2, and steps S51, S61, and S71 are executed between steps S7 and S8. It should be noted that steps S21, S51, S61, and S71 are related to... Figure 10 Steps S21, S51, S61, and S71 are the same. That is, after step S5, the control device 10 controls the attenuator 15 and the bleaching light source 13 to achieve volume holography. Figure 5 The predicted diffraction efficiency does not exceed that of volume holography. Figure 5 The set value of the diffraction efficiency. It should be noted that in step S1, the control device 10 sets the first threshold, the second threshold, and the third threshold according to the input of the set value of the diffraction efficiency.

[0108] Figure 16 This is a graph illustrating an example of the variation in diffraction efficiency of the volume hologram according to the fourth embodiment. Figure 17 This is a graph showing an example of the change in the amount of light emitted by a laser irradiating a volumetric hologram according to the fourth embodiment. Figure 18 This is a graph showing an example of the change in the amount of bleaching light irradiating the volume hologram according to the fourth embodiment. Figure 16The diagram illustrates the diffraction efficiency of volume holograms 60–62, which have different materials and thicknesses. Figure 17 The diagram illustrates the amount of light emitted by laser L1 when irradiating volume holograms 60–62 (that is, the sum of the amounts of light emitted by laser L2 and laser L3). Figure 18 The figure shows the amount of bleached light L8 illuminating the volume holograms 60-62.

[0109] like Figures 16-18 As shown, at time t0, exposure of volume holograms 60-62 begins. Upon initial exposure, the intensity of laser L1 increases to a predetermined value. After a period of time from time t0, the diffraction efficiency of volume holograms 60-62 begins to increase. Then, at times t6-t8, bleaching of volume holograms 60-62 begins, respectively. Afterward, by time t9, the intensity of laser L1 decreases. Finally, at time t9, the exposure and bleaching of volume holograms 60-62 concludes.

[0110] In this embodiment, the control device 10 calculates the volume hologram based on the measurement results of power meters 8 and 9 (the measured values ​​of the light intensity of lasers L6 and L7). Figure 5 The diffraction efficiency, based on the volumetric holography after exposure stops. Figure 5 The predicted value of the diffraction efficiency is used to control the attenuator 15 (the amount of light from laser L1) and the bleaching light source 13 (the amount of light from bleaching light L8). Therefore, even volume holograms with different materials and thicknesses can be produced with the set diffraction efficiency.

[0111] Furthermore, during the exposure of the volume hologram, it is bleached. The timing of the end of the bleaching process coincides with the end of the exposure. This ensures that the timing of the end of the exposure and the end of the bleaching are identical, thus suppressing changes in the diffraction efficiency of the volume hologram after exposure and during the bleaching process.

[0112] It should be noted that in the above embodiments, the first threshold and the third threshold may be the same or different. Additionally, the second threshold and the fourth threshold may be the same or different.

[0113] Alternatively, the above embodiments can be combined appropriately. For example, the control device 10 can set a timing for stopping the laser while controlling at least one of the laser light intensity and the bleaching light intensity based on a predicted value of the diffraction efficiency.

[0114] Industrial practicality The exposure apparatus disclosed herein can be used when exposing (manufacturing) volumetric holograms.

Claims

1. An exposure apparatus for exposing holographic optical elements, characterized in that: The exposure apparatus includes a first light source, a first detector, a second detector, a prediction device, a second light source, an adjustment device, and a control device. To detect the diffraction efficiency, or first diffraction efficiency, of the holographic optical element during the exposure process, the first light source illuminates the holographic optical element with light of a specified wavelength, i.e., first light. The first detector detects the amount of light from the first light. The second detector detects the amount of light from the second light, which is the first light diffracted by the holographic optical element. The prediction device calculates the first diffraction efficiency based on the detection results of the first detector and the second detector, and predicts the second diffraction efficiency of the holographic optical element after exposure stops based on the calculated first diffraction efficiency. The second light source illuminates the holographic optical element with a third light used to expose the holographic optical element. The adjusting device adjusts the amount of light from the third light. The control device controls the adjustment device based on the prediction result of the prediction device.

2. The exposure apparatus according to claim 1, characterized in that: The control device controls the adjustment device so that the second diffraction efficiency does not exceed the diffraction efficiency set by the user.

3. The exposure apparatus according to claim 1, characterized in that: When the difference between the second diffraction efficiency and the diffraction efficiency set by the user is large, the control device controls the adjustment device to increase the amount of the second light. On the other hand, when the difference between the second diffraction efficiency and the diffraction efficiency set by the user is small, the control device controls the adjustment device to decrease the amount of the second light.

4. An exposure apparatus for exposing holographic optical elements, characterized in that: The exposure apparatus includes a first light source, a first detector, a second detector, a prediction device, a third light source, and a control device. To detect the diffraction efficiency, or first diffraction efficiency, of the holographic optical element during the exposure process, the first light source illuminates the holographic optical element with light of a specified wavelength, i.e., first light. The first detector detects the amount of light from the first light. The second detector detects the amount of light from the second light, which is the first light diffracted by the holographic optical element. The prediction device calculates the first diffraction efficiency based on the detection results of the first detector and the second detector, and predicts the second diffraction efficiency of the holographic optical element after exposure stops based on the calculated first diffraction efficiency. The third light source illuminates the holographic optical element with bleaching light. The control device controls the amount of bleaching light based on the prediction result of the prediction device.

5. The exposure apparatus according to claim 4, characterized in that: The third light source includes a UV light source and a white light source.

6. The exposure apparatus according to claim 5, characterized in that: The control device controls the amount of UV light irradiated by the UV light source and the amount of white light irradiated by the white light source based on the prediction results of the prediction device.

7. The exposure apparatus according to claim 4, characterized in that: The exposure apparatus further includes a second light source, which illuminates the holographic optical element with third light for exposing the holographic optical element. The holographic optical element is simultaneously illuminated by the third light and the bleaching light during the exposure process.

8. The exposure apparatus according to claim 4, characterized in that: The control device controls the amount of bleaching light so that the second diffraction efficiency does not exceed the diffraction efficiency set by the user.

9. The exposure apparatus according to claim 4, characterized in that: When the difference between the second diffraction efficiency and the diffraction efficiency set by the user is large, the control device controls the second light source in a manner that reduces the amount of bleaching light. On the other hand, when the difference between the second diffraction efficiency and the diffraction efficiency set by the user is small, the control device controls the second light source in a manner that increases the amount of bleaching light.

10. An exposure method for a holographic optical element, characterized in that: include: The step of irradiating the holographic optical element with a third light for exposing the holographic optical element; In order to detect the diffraction efficiency, i.e., the first diffraction efficiency, of the holographic optical element during the exposure process, the step of irradiating the holographic optical element with light of a specified wavelength, i.e., the first light; The step of detecting the amount of light in the first light; The step of detecting the amount of light, i.e., the second light, diffracted by the holographic optical element; The steps are as follows: Based on the detection results of the first detector and the second detector, calculate the first diffraction efficiency, and predict the diffraction efficiency of the holographic optical element after exposure stops, i.e., the second diffraction efficiency, based on the calculated first diffraction efficiency. as well as The step of adjusting the amount of light from the third light based on the prediction results.

11. A method for exposing a holographic optical element, characterized in that: include: In order to detect the diffraction efficiency, i.e., the first diffraction efficiency, of the holographic optical element during the exposure process, the step of irradiating the holographic optical element with light of a specified wavelength, i.e., the first light; The step of detecting the amount of light in the first light; The step of detecting the amount of light, i.e., the second light, diffracted by the holographic optical element; The steps are as follows: Based on the detection results of the first detector and the second detector, calculate the first diffraction efficiency, and predict the diffraction efficiency of the holographic optical element after exposure stops, i.e., the second diffraction efficiency, based on the calculated first diffraction efficiency. as well as The step of adjusting the amount of bleaching light irradiating the holographic optical element based on the prediction results.

12. A method for manufacturing a holographic optical element, characterized in that: include: The step of irradiating the holographic optical element with a third light for exposing the holographic optical element; In order to detect the diffraction efficiency, i.e., the first diffraction efficiency, of the holographic optical element during the exposure process, the step of irradiating the holographic optical element with light of a specified wavelength, i.e., the first light; The step of detecting the amount of light in the first light; The step of detecting the amount of light, i.e., the second light, diffracted by the holographic optical element; The steps are as follows: Based on the detection results of the first detector and the second detector, calculate the first diffraction efficiency, and predict the diffraction efficiency of the holographic optical element after exposure stops, i.e., the second diffraction efficiency, based on the calculated first diffraction efficiency. as well as The step of adjusting the amount of light from the third light based on the prediction results.

13. A method for manufacturing a holographic optical element, characterized in that: include: In order to detect the diffraction efficiency, i.e., the first diffraction efficiency, of the holographic optical element during the exposure process, the step of irradiating the holographic optical element with light of a specified wavelength, i.e., the first light; The step of detecting the amount of light in the first light; The step of detecting the amount of light, i.e., the second light, diffracted by the holographic optical element; The steps are as follows: Based on the detection results of the first detector and the second detector, calculate the first diffraction efficiency, and predict the diffraction efficiency of the holographic optical element after exposure stops, i.e., the second diffraction efficiency, based on the calculated first diffraction efficiency. as well as The step of adjusting the amount of bleaching light irradiating the holographic optical element based on the prediction results.

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